Outcome of moderate carotid artery stenosis in patients who are asymptomatic

Purpose: The incidence rate of disease progression and stroke after the dia gnosis of a moderate (50% to 79%) carotid stenosis was determined by means of color-flow duplex scanning. Methods: During a 4-year period, 344 male veterans with moderate internal c arotid artery stenoses, on one or both sides, were examined at regular inte rvals for a mean period of 25 months. Carotid color-flow scans were obtaine d semiannually. Clinical follow-up was performed to determine the incidence rate of amaurosis fugax, transient ischemic attacks, nonhemispheric sympto ms, and strokes. Results: New neurologic symptoms developed in 75 patients (21.8%). Fifty-on e (14.8%) had ipsilateral symptoms during follow-up: 18 amaurosis fugax (5. 2%), 14 transient ischemic attacks (4%), 5 nonhemispheric symptoms (1.4%), and 14 strokes (4%). Twenty-four patients (6.9%) had contralateral symptoms : 20 strokes (5.8%) and 4 transient ischemic attacks (1.2%). Life-table ana lysis showed that the annual rate of ipsilateral neurologic events was 8.1% , and the annual rate of stroke was 2.1%. Seventy-five patients (22%) died in the follow-up period. Disease progression to 80% to 99% stenosis or occl usion occurred in 71 of 458 vessels (15.5%). The internal carotid arteries that showed evidence of disease progression had a significantly higher init ial peak systolic velocity (251 vs 190 cm/s; P < .0001) and end diastolic v elocity (74 vs 52 cm/s; P < 0.0001). Black patients and patients with ische mic heart disease were at a higher risk for disease progression. We could n ot identify any atherosclerotic risk factors that reliably predicted patien ts in whom future ipsilateral neurologic symptoms were more likely to devel op. However, there was an increased risk of stroke associated with progress ion of disease. Conclusion: Patients who are asymptomatic and who have moderate carotid ste noses are at significant risk for neurologic symptoms and death, but have a relatively low incidence rate of ipsilateral events. The initial flow char acteristics in the stenotic vessel are predictive of future disease progres sion, but they are not helpful in identifying patients in whom symptoms wil l develop.